Kinematics of the Wind Field. Assignment 12. Due April 6

Purpose: (1) to analyze the kinematics of the wind field as diagnosed by an operational model. (2) examine the evolution of the jet stream over a 48 h period. (3) become familiar with the use of garp to display and diagnose weather conditions.

Review the information on kinematics in the Djuric text.

Graphics for the 48 h period beginning at 00z 31 March will be used.

Select Garp from the program menu and then do the following:

select Model Plan Projection
select Eta model
select pressure vertical coordinate
select 300 for Level 1
select all of the forecast times for the Eta model run on 990331/0000
select wind_kts

Animate and step thru the images. Overlay isotachs in kts. How do the jets over the western U.S. evolve with time during the 48 h period?

Overlay the absolute vorticity on the wind field (you will need to type in the following in the lower right box AVOR(OBS) ). Describe the evolution of the upper level trough and the changes in absolute vorticity.

Overlay VOR(OBS)(relative vorticity). Select a couple of features and interpet the features in terms of absolute and relative vorticity.

Overlay the divergence of the wind field on the vector winds.How did the divergence field evolve with time?

How do the changes in the kinematics of the wind field relate to the changes in the weather over Utah?

Keep your answers short and focussed. Email responses to me.